How long has it been since you started? Is it successful for the most part? Even in 30°F weather?
I assume your potential low temperature is 30 F. That's good information but what is your potential warmest ambient temperature? Also, how many chicks are you talking about?
My brooder was in the coop when I was in Northwest Arkansas. One issue I had when brooding in the winter was the temperature swings. I saw the temperature go from below freezing to the 70's F in less than a day. Or go the other way. A brooder needs to have a spot warm enough in the coldest temperatures but also a spot cool enough in the warmest temperatures. To me that is something you need to keep in mind.
I used a 3' x 6' brooder with broods of around 20 chicks in temperatures as low as the mid-20's F. I used a heat lamp (two in winter for redundancy) and was not that worried about a fire risk because I took precautions. I held the lamps in place with wire (could have used chain) so it could not fall. I did not use the clamp, I consider those dangerous. I did not use string or plastic cordage that could burn or melt. Wire or chain so it is secure.
The brooder floor was 1/2" hardware cloth, the poop fell straight through. The brooder was elevated about 18" so I could fit bins underneath to catch the poop, made it easy to clean underneath. That way I did not need any bedding so nothing to burn. In winter I put a piece of plywood under the heat lamp to hold the heat in, to clean it I just turned it on its side to let the poop fall through the hardware cloth. That brooder stayed very dry and clean.
The brooder was positioned under the roosts. The top was a sheet of plywood so it acted as a droppings board. In winter I wrapped the sides with clear heavy plastic to help hold the heat in and keep the wind out. That plastic went all the way to the floor to keep wind out. I weighted the ends of that plastic down at the floor to keep the hens out from under the brooder, occasionally one would get behind the bins and make a nest. Aggravating things. I used 2x4's to weigh it down.
I had ventilation up high so the far end could cool off when the weather warmed up. I kept one end toasty in the coldest weather but the far end could cool off. Some mornings I found ice on the far end. When the weather warmed up I'd find the chicks on the far end. I put the water in the heated area so it would stay thawed. Many people would be surprised at how much time the chicks would spend in the cooler areas but when they are very young they spend a lot of time in the heated area.
Many people use a heating pad cave in cold weather. I'll include a link to Blooie's thread about it. It's a long thread and you have to kind of dig through it to get all the precautions and how to set it up, but it can work. The fire warning on this one came from Blooie's husband who was a fire fighter. Do not use an old heating pad. They can get brittle and the wire can break, short out, and start a fire. If you set it up properly and use good equipment I consider this method very safe and effective any time of the year.
https://www.backyardchickens.com/th...d-in-the-brooder-picture-heavy-update.956958/
You might do some research on the hover, maybe search under "Ohio brooder". This method was used in World War II to raise a large number of chicks with electrical efficiency. Don't waste energy. The basic idea is to use hot air rising. You build a shallow box and hang it with the opening down. Put a heat source under it so the box traps the heat. The chicks can go in and out as they wish. Like everything else the details of how you set it up are important.
With all of these methods many people are surprised at how much time the chicks spend in areas not heated or how soon they start sleeping in unheated areas. I can remember a few stories where people kept putting the chicks under the heat plate or in the heating pad cave when the chicks did not want to be there. I let mine decide where they want to be but make sure I have a spot warm enough and cool enough so they have the option.
The reason I asked about the number of chicks is a member a few years back did a comparison from when she used the heating pad cave and a heat lamp. The only thing I remember from that was that the heat lamp worked better for larger numbers of chicks, maybe in the upper teens. If you have a very large number of chicks the hover could be a good option.